Peroxidic sulfonic acids and salts



Patented Oct. 3, 1950 PEROXIDIC SULFONIC ACIDS AND SALTS Frederick F.Rust, Oakland, and Alan R. Stiles and William E. Vaughan, Berkeley,Calif., assignors to Shell Development Company, San Francisco, Calif., acorporation of Delaware No Drawing. Application February 21, 1949,Serial No. 77,692

' Claims. (01. 260-505) This invention relates to sulfonic acids (andtheir metal salts) in which the organic portion of the molecule containsa peroxy (-O-O) group. The invention provides a new class of compounds,peroxidic sulfonic acids (and salts thereof) in which the sulfo (SO3H)group: replaces one or more hydrogen atoms of an organic peroxide of theclass defined below.

This application is a continuation-in-part of our copending applicationSerial No. 792,840, filed December 19, 1947, now Patent Number2,519,403. Our earlier filed application describes and claims a novelreaction process by which certain organic peroxides can besulfohalogen'ated to form the novel peroxidic sulfonyl halides, whichare also described and claimed therein. This application describes andclaims the class of novel compounds which can be prepared by the actionof water or a metal hydroxide upon certain peroxidic sulfonyl halidesunder reaction conditions suitable for the conversion of an alkyl oraryl sulfonyl halide to a sulfonic acid or salt.

The invention provides polyfunctional compounds which are eithersulfonic acids or the salts of sulfonic acids and which are at the sametime, substituted peroxides of the following class: peroxides composed'ofv two tertiary hydrocarbon radicals or their halogen-analogs thatcontain one or more chlorineor bromine atoms, connected by a peroxygroup attached to a tertiary-carbon atom in each radical; and whichperoxides are substituted by the replacement of one or more hydrogenatoms with sulfo groups or, in the case of the salts, with -SO3M groupswhere M represents a metal.

In general, the peroxy grouping in an organic molecule is so unstablethat a compound containing it, if it reacts under a given set ofconditions, undergoes a reaction involving the bonds of this grouping;We have now discovered, however, that when the grouping is containedbetween two tertiary carbon atoms, not only can the compound besulfohalogenated, but derivatives of the sulfonic acids such as2-methyl-g -tertiary-butyl- 2 peroxypropanesulfonic acid,bis(sulfo-tertiarybutyl) peroxide and 4 tertiary butylperoxy 4methylcyclohexanesulfonic acid; aromatic sulfonic acids such as 2--dimethylbenzylperoxy) ,Z-methylpropanesulfonic acid, 2-phenyl-2-(amethyl 4(chloro tertiary butylperoxy)pentanesulfonic acid; and metalsalts of the s-ulfo-nic acids such as the potassium, sodium, calcium,barium, and magnesium salts of the above sulfonic acids.

A preferred class of compounds provided by the invention consists of thesulfonic acid which are substituted di-tertiary-alkyl peroxides, ortheir halogen-analogs that contain one or more chlorine or bromineatoms, in which the substituted peroxide groups consist of at leastonesuiio group; and the metal salts oi'such sulfonic acids in which themetallic ion has a normal valence of-not more than two.. The preferredclass is typified by acids such as 2-methyl-2-tertiary=-butylperoxypropanesulionic acid, bis(sulfo-tertiary-butyDperoxide, and3-methy1-3-(bromm tertiary-butylperoxy)butanesulfonic acid; and saltssuch as the sodium, potassium and calcium salts of such acids.

As is the case with substantially any organic compound, the compoundsprovided by the present invention can be prepared by various methods ofsynthesis. We have found that a particularly suitable method ofpreparing them comprises the conversion of the corresponding sulfonylhalides by any of the general methods, which do not involve thenecessary employment of high temperature, for converting alkylor arylsulfonyl halides to acids or metal salts of the acids.

A particularly suitable method of producing sulfonyl halides suitablefor conversion to the compounds provided by the present inventioncomprises the sulfochlorination of the corresponding peroxide bycontacting it with a mixture of sulfur dioxide and chloride, while it ismaintained inthe liquid phase, in the presence of 'actinic radiationsand at av temperature below its decomposition temperature (the processof our earlier filed application). .When a (ii-tertiary- .alkylperoxide, or its halogen-analog, that, conyerted, without isolation fromthe reaction mixture, to a sulfonic acid salt by the addition of anaqueous solution of a metal hydroxide, and to a sulfonic acid byacidification of the above mixture after the addition of base, or,particularly in the case of the sulfonyl bromides, by the addition ofwater to the sulfohalogenation reaction mixture.

The particularly preferred class of sulionic acids provided by thepresent invention comprises monosubstituted di-tertiary-alkyl peroxides,or the halogen-analogs of such peroxides that contain one or morechlorine or bromine atoms, in which substituted peroxides thesubstituent is a sulfo group. The particularly preferred class ofsulfonic acid salts comprises the alkali metal salts such as the sodiumpotassium and lithium salts of the particularly preferred sulfcnicacids.

The compounds provided by the present invention are particularlyvaluable in that they render available peroxidic materials having theresistance to violent decomposition upon impact or during storagecharacteristic of the di-tertiaryalkyl :peroxides, and having, at thesame time,

the characteristics of ionization and solubility of the sulfonic acidsand metal sulfonates. We have tested these compounds in polymerizationreactions and have found they initiate 'chain reactions in a manneranalogous to known organic peroxides. We have found that they exhibit apronounced tendency to dissolve in ionic media, particularly in analkaline media and, as illustrated by Example II, we have found them tobe particularly resistant to violent decomposition when subjected tophysical impact.

The following examples illustrate in detail individual sulfonio acidsand metal sulfonates provided by the present invention as well asmethods for their production. As man variations in the structure of theacids and salts are within the scope of the invention, the invention isnot to be construed as limited to the particular compounds specified inthe examples or to the products of the particular reactions describedtherein.

Example I The preferred method of preparing starting compounds, fromwhich the compounds provided by the present invention can be prepared bythe conversion reactions applicable to the alkyl or aryl sulfonylhalides, is illustrated by the following detailed example.

One mole (146 g.) of di-tertiary-buty1 peroxide is placed in atransparent vessel illuminated by a 500 Watt bulb at a distance of aboutsix inches. The peroxide is maintained at a temperature of between 6 and8 C. while a gaseous mixture of sulfur dioxide and chlorine in molarproportions of 3:2 is introduced beneath the surface of the peroxide.The gaseous mixture is passed mat a rate introducing 0.3 mole of sulfurdioxide and 0.2 mole of chlorine in about 90 minutes.

The sulfonyl chloride may be converted by the procedures illustrated bythe following examples while dissolved in the reaction products, or' itmay be isolated and purified, for exampleby subjecting the reactionmixture to a low pressure fractional distillation to remove thedissolved gases and unreacted peroxide and, if desired, distillation ofthe sulfonyl chloride.

The sulfonyl chloride prepared in this manner is 2-tertiary-butylperoxy2 methy1propanesulfonyl chloride, a water-white liquid boiling from 4753- C. at 1 mm. pressure and having the formula:

CH3 CH5 Potassium 2-tertiary-butylperoxy 2 methylpropanesulfonate isprepared by adding 50 grams of a 50% aqueous solution of potassiumhydroxide to grams of 2-tertiary-butylperoxY-Z-methylpropanesulfonylchloride, maintained at about C. The potassium sulfonate is isolated byfiltering the reaction mixture.

A sample of potassium Z-tertiary-butyl-peroxy-2-methylpropaneesulfonatewas prepared by treating the crude sulfochlorination product produced bythe process described in Example I in accordance with the aboveprocedure. The sample was dried and upon analysis found to have thefollowing composition:

Th stability of the salts of the sulfo-substituted organic peroxidesprovided by the invention to conditions of physical shock wasdemonstrated by placing a sample of dry potassiumZ-tertiarybutyl-peroxy-2-methylpropanesulfonate crystals upon a metalplate and striking them a sharp blow with a hammer. The crystals did notdetonate although the impace was sufiicient to cause a shar explosionfrom the salt of an organic peroxide such as potassium perbenzoate, or asolid peroxide such as diacetyl peroxide.

Example III An alcohol solution of 2-tertiary-butylperoxy-Z-methylpropanesulfonic acid is prepared by dissolving 10 grams ofpotassium Z-tertiary-butylperoxy-Z-methylpropanesulfonate in 50 cc. ofabsolute ethanol at about 20 0., adding anhydrous hydrochloric aciduntil the mixture is acid to moist litmus paper, and removing theprecipitated salt by filtration.

A solution of 2-tertiary-butylperoXy-2-methylpropanesulfonic acid wasprepared by treating a sample of the potassium salt prepared fromsulfochlorinated di-tertiary-butyl peroxide, by the procedure describedin'Example II, by treating the salt in the above manner. The solutionwas colorless and was miscible with water, but the free acid was foundto be unstable when the alcohol was removed over a water bath underatmospheric pressure, or at room temperature under reduced pressure. Theacid has the formula on, em

omo-o- 0H:SO|H

Ha Ha Example IV Potassium 2-(,a-diinethyl-para-chlorobenzylperoxyl-Z-parachlorophenylpropanesulfonate the formula,

on:I CH; 016 c-o-o-o-omsosx and is a solid compound which is thermallyor photochemically decomposed into free radicals and which exhibits theionic properties of a high molecular weight organic sulfonic acid salt.

Example V Calcium 2-tertiary-butylperoxy-2 methylpropanesulfonate isprepared by adding grams of calcium hydroxide in the form of a saturatedaqueous solution to 25 grams of aZ-tertiary-butylperoxy-Z-methylpropanesulfonyl chloride and recoveringthe solid precipitate.

The calcium sulfonate has the formula,

. and is a solid compound which is thermally or photochemicallydecomposed into free radicals and which exhibits the properties of ahigh molecular weight sulfonic acid salt.

Example VI The dipotassium salt of bis(sulfo-tertiarybutyl) peroxide isprepared by adding 50 grams of 50% aqueous potassium hydroxide to gramsof bis(chlorosulfonyl-tertiary-butyl) peroxide, and recovering the solidprecipitate.

The dipotassium salt has the formula,

and is a solid compound which is thermally or photochemically decomposedinto free radicals and which exhibits the properties of a salt ofadisulfonic acid.

We claim as our invention:

1. Potassium 2-tertiary-butylperoxy-2-methylpropanesulfonate.

2. The dipotassium salt of bis(sulfo-tertiarybutyl) peroxide.

3. Potassium 2 (a1pha,alpha -dimethylparachlorobenzylperoxy) 2 parachlorophenylpropanesulfonate.

4; Calcium 2-tertiary-butylper0xy-2 methylpropanesulfonate.

5. 2-tertiary-butylperoxy-2-methylpropanesulfonic acid.

6. Tertiary-alkylperoxyalkanesulfonic acids in which the alkylperoxyradical is attached to a tertiary carbon atom.

7. Alkali metal tertiary-alkylperoxyalkanesulfonates in which thealkylperoxy radical is attached to a tertiary-carbon atom.

8. sulfonic acids in which the sulfonic acid group replaces a hydrogenatom of a peroxide which consists of two tertiary-hydrocarbon radicalsconnected by a peroxy group attached to two tertiary-carbon atoms.

9. A compound of the group consisting of -a sulfonic acid and the metalsalt of the sulfonic acid, which sulfonic acid is a substituted peroxideof the class consisting of peroxides wherein the peroxy group attachedto a tertiary-carbon atom in each of two chloro-substitutedtertiary-hydrocarbon radicals, in which substituted peroxide thesubstituents consist of at least one member of the group consisting ofthe'sulfonic acid group and the sulfonic acid salt groups.

10. A compound of the group consisting of a sulfonic acid and the metalsalt of the sulfonic acid, which sulfonic acid is a substituted peroxideof the class consisting of peroxides wherein the peroxy group attachedto a tertiary-carbon atom in each of two radicals of the groupconsisting of tertiary-hydrocarbon radicals, chloro-substitutedtertiary-hydrocarbon radicals and bromosubstituted tertiary hydrocarbonradicals containing at least one halogen atom of the group consisting ofchlorine and bromine atoms, in which substituted peroxide thes-ubstituents consist of at least one member of the group consisting ofthe sulfonic acid group and the sulfonic acid salt groups.

FREDERICK F. RUST. ALAN R. STILES. 1 WILLIAM E. VAUGHAN.

No references cited.

1. POTASSIUM 2-TERTIARY-BUTYLPEROXY-2-METHYLPROPANESULFONATE.